So far, it is the rivers of the region that have suffered the greatest change in canyon country. This is not the fault of Major John Wesley Powell, a largely self-taught naturalist, geologist and ethnologist. Powell went on to organize and lead some of the most important exploring expeditions since the days of Lewis and Clark ...

In May 1869, he set off on one of the great river journeys of history down the Green and Colorado rivers and through the Grand Canyon, surviving house-sized rapids and frequent wrecks. Powell went on to write a best-seller about the trip, Exploration of the Colorado River of the West and Its Tributaries, published in 1875. More importantly, his newfound fame enabled him to persuade Congress to support a major survey of the entire Plateau Province.

Powell's 1878 Report on the Lands of the Arid Region of the United States punctured immediately one of the fondest visions of the boomers: the notion that the West, like the eastern third of the nation, could be made to support not only thriving metropolises but millions of small independent farms ...

The boomers refused to listen. During the 1890s, "irrigation congresses' began to convene regularly, calling for the government to step in to build irrigation works in the West that would provide the water for "a million 40-acre farms." The 1893 congress, held in Salt Lake City, invited the major to speak. Bad idea. Powell had not changed his mind since 1878; if anything, he had grown even more certain that the dreams were not going to work in the arid West.

"I wish to make it clear to you," he told them, "there is not enough water to irrigate all these lands; there is not sufficient water to irrigate all the lands that could be irrigated, and only a small portion can be irrigated ... I tell you, gentlemen, you are piling up a heritage of conflict ..."

Still, the boomers would not listen. In 1902, they persuaded Congress to pass the Newlands Act, creating the Reclamation Service (later to become the Bureau of Reclamation). It proceeded to build the greatest water works projects in the history of humankind.